1. Field of the Invention
The present invention relates, in general, to special effects for movies, animatronics, toys, and other applications relating to adding realism to artificial eyes and, more particularly, to devices that mimic or simulate natural constriction and dilation of a pupil in an eye.
2. Relevant Background
Surprisingly, there are large numbers of applications for “expressive” artificial or animatronic eyes that function similarly to the eye they are imitating. For example, the movie industry often has to build a creature such as dinosaur, an alien, a robot, or other character that has eyes that behave as expected for that particular creature. Realistic eyes are also often desirable in toys such as in stuffed animals and robotic characters. If an eye is fixed or unchanging, the overall effect provided by the creature or character quickly loses its effectiveness. Expression is sometimes provided by moving an entire eye to look another direction or by moving the surrounding skin or features such as mechanical eyelids or eyebrows.
To obtain more realistic eye effects, it is desirable to imitate the internal functioning of the eye including changes of the pupil. For example, in the human eye, the iris is a colored ring that surrounds the pupil, which appears as a black hole in the middle of the iris. The pupil is dilated or expanded in size by movement of the iris that is activated by muscles to allow more light into the eye such as when conditions are dark, and the pupil is contracted or shrunk in size to decrease the amount of light entering the eye such as when the eye is exposed to bright light. To imitate human eyes, it is desirable to selectively change the size of the pupil or to dilate and constrict the pupil (or surrounding iris). Alternatively, it is desirable to effectively simulate such dilation and contraction of the pupil to make the eye appear to be expressive or at least reactive to light conditions.
Existing pupil simulation techniques have generally concentrated on mechanical shuttering effects similar to movement of the iris or have used relatively complex electronic circuitry to change a size of a displayed pupil. While providing some desirable special effects including more life-like eyes, there is an ongoing demand for expressive eye devices that effectively simulate the dilating and constricting of a pupil. Preferably, such devices provide for selective or automated control of pupil size and are relatively simple and inexpensive to fabricate, install, maintain, and operate.